Question

Should our cement basement floor have been sealed before vinyl tiles were installed? We see condensation and white salt-looking crystals in

Asked by
nancy delony Marysville, WA

We recently had freefit vinyl tiles installed on top of an unsealed cement basement floor. There was laminate there before with no condensation problems. Now we see condensation and white salt-looking crystals in between the edges everyday. Should a sealant have been put down first? The contractor said that would make it worse.Is he just not wanting to take up the floor? Does the rubber in the vinyl make a difference in condensation where the laminate did not?

Answer

If there is no vapor barrier below the concrete slab, sealing from the top will not eliminate the problem. Most sealers applied to the top of a concrete slab which does not have a vapor barrier below will peel up over a period of time and will become a maintenance item.

You have two options:

remove the concrete slab and install a minimum 6 mill vapor barrier and re-pour the slab, or

install a subfloor which is on raised on standoff which allow air to flow below to allow the moisture to evaporate removing the ability for mold and mildew to grow.

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